EP1925003A2 - Siox:si composite material compositions and methods of making same - Google Patents

Siox:si composite material compositions and methods of making same

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Publication number
EP1925003A2
EP1925003A2 EP06801634A EP06801634A EP1925003A2 EP 1925003 A2 EP1925003 A2 EP 1925003A2 EP 06801634 A EP06801634 A EP 06801634A EP 06801634 A EP06801634 A EP 06801634A EP 1925003 A2 EP1925003 A2 EP 1925003A2
Authority
EP
European Patent Office
Prior art keywords
sio
composite
conductive
powder
sintered
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP06801634A
Other languages
German (de)
French (fr)
Other versions
EP1925003A4 (en
Inventor
David E. Stevenson
Li Q. Zhou
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wintek Electro Optics Corp
Original Assignee
Wintek Electro Optics Corp
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Filing date
Publication date
Application filed by Wintek Electro Optics Corp filed Critical Wintek Electro Optics Corp
Publication of EP1925003A2 publication Critical patent/EP1925003A2/en
Publication of EP1925003A4 publication Critical patent/EP1925003A4/en
Withdrawn legal-status Critical Current

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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/06Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
    • H01B1/12Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances organic substances
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/14Conductive material dispersed in non-conductive inorganic material
    • H01B1/16Conductive material dispersed in non-conductive inorganic material the conductive material comprising metals or alloys
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00Silicon; Compounds thereof
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/14Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silica
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/628Coating the powders or the macroscopic reinforcing agents
    • C04B35/62844Coating fibres
    • C04B35/62878Coating fibres with boron or silicon
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/64Burning or sintering processes
    • C04B35/645Pressure sintering
    • C04B35/6455Hot isostatic pressing
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34Sputtering
    • C23C14/3407Cathode assembly for sputtering apparatus, e.g. Target
    • C23C14/3414Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/04Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of carbon-silicon compounds, carbon or silicon
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30Constituents and secondary phases not being of a fibrous nature
    • C04B2235/34Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3418Silicon oxide, silicic acids, or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30Constituents and secondary phases not being of a fibrous nature
    • C04B2235/42Non metallic elements added as constituents or additives, e.g. sulfur, phosphor, selenium or tellurium
    • C04B2235/428Silicon
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/74Physical characteristics
    • C04B2235/77Density
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/29Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2982Particulate matter [e.g., sphere, flake, etc.]
    • Y10T428/2991Coated

Definitions

  • This invention relates to material compositions primarily composed of electrically non-conductive silicon oxide material in combination with fractions of materials that render the overall composition electrically conductive. [0002] 2. Related Art
  • SiO x oxides of silicon
  • SiO 2 oxides of silicon
  • One of the principal methods for producing such thin films is by a physical vapor deposition process known as radio frequency sputtering. This method utilizes non-conductive silicon dioxide material as the source material for the creation of the silicon dioxide thin film coatings. A high frequency ac-voltage, typically 13.56 MHz is applied capacitively to the target. In one phase, gas ions of the plasma are accelerated toward the target and cause material at the surface of the target to be detached as a result of the bombardment with the gas ions.
  • Direct current (DC), pulsed DC or medium to low frequency alternating current (AC) sputtering processes do not have such limitations.
  • DC and AC processes require the use of silicon as the source material for the SiO 2 coating.
  • silicon To utilize silicon as the deposition source material, it must be made sufficiently conductive either by doping with a suitable dopant such as boron, arsenic or by the addition of small amounts of aluminum or other suitable metals.
  • a suitable dopant such as boron, arsenic or by the addition of small amounts of aluminum or other suitable metals.
  • To use such silicon targets to create SiO 2 thin films via DC or AC sputtering also requires that large amounts of oxygen be introduced into the sputtering process. The resultant process is referred to as reactive sputtering. The oxygen reacts with the silicon during the sputtering process to yield SiO 2 .
  • SiO 2 films typically require that O 2 gas pressure be 30 - 50% of the total gas pressure in the vacuum chamber. This can result in a significant process mismatch in terms of the oxygen requirements, as compared to that required for other sputtered thin films which may be deposited using the same vacuum vessel. The presence of significant O 2 in the vacuum chamber also slows the deposition rate through collisions with the silicon.
  • SiO 2 films made by DC and AC sputtering from silicon or Si:Al targets generally are not sufficiently dense and crystalline as a result of the characteristics of reactive deposition to render them suitable for many semi-conductor, flat panel and optoelectronics applications.
  • the SiO 2 film compositions produced by such reactive processes generally exhibit less useful optical, mechanical and chemical durability properties compared to those produced by RF sputtering of non-conductive SiO 2 targets.
  • SiO x silicon oxide-based material compositions (with the general formula SiO x ) that include a sufficient amount of silicon to render the composition electrically conductive.
  • the SiO x : Si material compositions of this invention are suitable for any application calling for electrically conductive SiO x -based material.
  • One such use is as a target material for use in DC (including DC-pulsed) or AC sputtering processes to produce high quality SiOx thin film coatings with the addition of only small amounts of O 2 during the deposition process, since the presence of SiO x in the target material serves as a source of oxygen in the vessel thereby decreasing the amount of oxygen gas that typically needs to be fed into the vessel during reactive sputtering DC or AC processes. This enables the production efficiencies of DC and AC sputtering to be used to produce SiO x coatings with properties that can be equivalent to those produced by the less efficient and more costly RF sputtering method.
  • the SiO x Si material of the invention is composed of the constituent materials of electrically non-conductive SiO x and an amount of Si that has been doped and combined with the SiO x in a manner that physically unites the materials to render the overall SiO x -based composition electrically conductive.
  • These material compositions although primarily composed of insulating silicon dioxide, exhibit good electrical conductivity while retaining many of the other intrinsic material properties of the silicon oxide.
  • Such materials can be fabricated in solid bulk forms such as plates, rods and tubes. In addition these bulk materials can be reduced (or reground) to powder form with such powders retaining the electrically conductive properties of the bulk material for use alone or with other materials in the formation of various articles of manufacture.
  • Si material which, although primarily composed of insulating SiO x material, has good electrical conductivity due to the presence of the Si material.
  • This material may find use in many applications that require the optical, thermal, mechanical, or chemical properties of SiO x but which also require electrical conductivity to be useful.
  • the electronic properties of this material can be adjusted based on the ratio of the constituents of electrically conductive doped Si, SiO x and in some embodiments small fractions of various metals.
  • particles of this conductive Si:SiO x material may be mixed or added to other materials to provide or enhance electrical conductivity or other useful properties.
  • Figure 1 is a schematic illustration of an article made of the Si: SiO x material;
  • Figure 2 is a schematic illustration showing further details of the material; and
  • Figure 3 is version of the material in particulate form.
  • the present invention is directed to the formation of composite silicon oxide:silicon (SiO x : Si) material that is rendered conductive by the selection of starting materials and the process by which they are combined to form the composite.
  • SiO x silicon oxide:silicon
  • the process starts out with a silicon oxide, SiO x powder (e.g., SiO 2 powder) which is substantially electrically non-conductive.
  • the SiO x powder is united with electrically conductive Si material in a manner that protects the Si against substantial oxidation during the process and which renders the overall composite electrically conductive while preserving the characteristics of each of the SiO x and Si materials.
  • One approach contemplated by the invention starts out with a blend of SiO 2 and conductive Si powders.
  • the blended powder is compacted and sintered to form an article that has the properties of being similar to silicon oxide but with low resistivity, and thus they find use in many applications.
  • one particular usage for such a material is as a sputtering target suitable use in a DC or AC thin film sputtering process.
  • the conductive silicon component of the powder blend is prepared by crushing and then grinding doped silicon (such as boron p-type doped silicon) into a powder.
  • doped silicon such as boron p-type doped silicon
  • the doping of the silicon material may be achieved by adding a suitable n or p dopant to molten silicon prior to growing or casting the amorphous single or poly phase crystal of the silicon. The concentration and uniformity of these dopant atoms determine the specific electrical characteristics of the silicon.
  • the invention contemplates that various approaches can be employed to blend the particles of silicon oxide and conductive silicon and that variations can occur in the size of the particles and the ratio of the silicon oxide to doped silicon particles in order to alter the electrical conductive properties or resistivity of the end product.
  • the composition of the base silicon oxide powder is greater than 50% by weight, and that of the conductive silicon powder is greater than 10% by weight, with the silicon oxide preferably making up the majority of the powder blend.
  • the powders may be blended together in a pot using zirconia balls as milling media until the average particle size of the blended powder is reduced to less than 5 ⁇ m.
  • the powder is preferably placed in a metal containment unit and then heated under vacuum conditions to eliminate residual moisture.
  • the containment unit is evacuated and sealed and then placed in a hot isostatic chamber and then heated to a temperature and pressure sufficient to densify and sinter the silicon oxide and doped silicon particles.
  • the container is preferably one which can withstand the heat and pressure of the hot isostatic-pressing environment, but which flows plastically under the heat and pressure so as to consolidate and densify the powder material within the container. Once densified, the resultant article of silicon oxide-doped silicon material is removed from the container.
  • the resulting composition is preferably densified to at least 90% of theoretical density, and preferably at least 95% of full theoretical density, and still more preferably greater than 99% of full theoretical density.
  • the powder is subjected to hot isostatic pressure (HIP) at temperatures of between 1200 to 145O 0 C and under pressures exceeding 20 kpsi. More particularly, the preferred process involves hot isostatic press heating to 1000 0 C under vacuum conditions and then gradually applying the pressure to more than 20 kpsi while increasing the temperature to between 1200 to 1350 0 C.
  • the -resultant sintered article 10 has a resistivity value of less than 200 ⁇ -cm.
  • the article or target has resistivity less than 150 ⁇ -cm and still more preferably below 20 ⁇ -cm and still further more preferably at or below 10 ⁇ -cm.
  • the range of resistivity contemplated by the invention is in the range of about 10 ⁇ -cm or less to about 200 ⁇ -cm.
  • Figure 1 schematically illustrates an article 10 made of the inventive material.
  • Figure 2 schematically illustrates details of the material structure in which the non-conductive silicon oxide is present in a web of electrically conductive silicon.
  • the conductive silicon serves as a conductive web that renders the overall material conductive.
  • Figure 3 shows a version of the material in particulate form.
  • This material can be prepared by regrinding the sintered SiO x : Si material resulting from the process described above, or may be formed directly in particulate form by a process in which SiO x particles are coated with molten electrically conductive Si in a protective non- oxidizing atmosphere such as argon to cause the Si to at least partially coat and unite with the SiO x particles, while protecting the molten Si against oxidation in the process.
  • the resultant composite particles can be mixed with other such particles and/or blended with an amount of uncoated silicon oxide particles and thereafter sintered to form an article.
  • the amount of the conductive composite particles will be that amount which is needed to achieve the desired electrical conductivity properties.
  • the invention contemplates that enough of the composite particles are present to provide a conductive path through the bulk of the sintered material.
  • the article can be used in a number of different applications, such as a target in a direct current (DC) or low to medium frequency alternating (AC) sputtering process for producing silicon oxide coatings.
  • DC direct current
  • AC medium frequency alternating
  • the invention contemplates that various manufacturing methods can be used to prepare the material that yield the same desirable characteristics and properties described above. These alternative methods can be used with or without the hot isostatic pressing.
  • Such additional processes include vacuum plasma spraying of the Si material onto the SiO x material in an inert gas atmosphere to preclude oxidizing the Si; vacuum casting ("melt casting") of the materials to connect Si grains of the blend in the presense of the SiO x grains to yield a conductive network; vacuum hot pressing of the materials in an inert gas atmosphere; and inert gas microwave melting and solidification.
  • the invention also contemplates various post-treatment methods for rendering the Si conductive in the company of SiO 2 .
  • the Si is alone in powder form or united with the SiO x in reground powder form, with the Si initially being non-conductive.
  • One alternative approach for making the silicon conductive is by means of thermal gas diffusion in non-oxygen atmosphere using a gas such as Arsine, AsH 3 composition.
  • Another approach is ion implantation with dopants such as Boron.
  • the dopant such as Arsenic, Gallium, or Phosphorous could be added in powder form to reground non-conductive Si:SiO x powder and then sintered in a non-oxygen atmosphere.
  • Still another approach to post- treatment doping of initially non-conductive Si is to mix metal powder such as Al, Mg, Sn, In, Mn, Zn, Bi, Cd, Se, and/or Ga with reground non-conductive Si:SiO x powder and then sinter in a non-oxygen atmosphere.
  • metal powder such as Al, Mg, Sn, In, Mn, Zn, Bi, Cd, Se, and/or Ga

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  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
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  • Inorganic Chemistry (AREA)
  • Structural Engineering (AREA)
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  • Chemical Kinetics & Catalysis (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Physics & Mathematics (AREA)
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Abstract

Silicon oxide and electrically conductive doped silicon materials are sintered in a protective environment to yield a composite SiOx:Si material that exhibits the properties of SiOx, and yet is electrically conductive due to the presence of Si. Such a composite material finds many uses, such as a target for DC and/or AC sputtering processes to produce silicon oxide thin films for touch-screen applications, barrier thin films in LCD displays and optical thin films used in a wide variety of applications.

Description

SiOvSSi COMPOSITE MATERIAL COMPOSITIONS AND METHODS OF
MAKING SAME
BACKGROUND OF THE INVENTION
[0001] 1. Technical Field
This invention relates to material compositions primarily composed of electrically non-conductive silicon oxide material in combination with fractions of materials that render the overall composition electrically conductive. [0002] 2. Related Art
One important commercial application for such material compositions is thin film technology. Many architectural, automotive, integrated circuit, flat panel display and optical devices require thin films of oxides of silicon (SiOx), such as SiO2. [0003] One of the principal methods for producing such thin films is by a physical vapor deposition process known as radio frequency sputtering. This method utilizes non-conductive silicon dioxide material as the source material for the creation of the silicon dioxide thin film coatings. A high frequency ac-voltage, typically 13.56 MHz is applied capacitively to the target. In one phase, gas ions of the plasma are accelerated toward the target and cause material at the surface of the target to be detached as a result of the bombardment with the gas ions. In the other phase, the charge on the target surface is neutralized with the result that no sputtering occurs during this periodic phase. Although this method produces suitable silicon dioxide thin film coatings, it has the limitations of requiring the use of expensive and complex high frequency power supplies, low deposition rates for the formation of the SiO2 thin film coatings, and inherent limitations on the uniformity of SiO2 coatings that can be created with such method.
[0004] Direct current (DC), pulsed DC or medium to low frequency alternating current (AC) sputtering processes do not have such limitations. However, DC and AC processes require the use of silicon as the source material for the SiO2 coating. To utilize silicon as the deposition source material, it must be made sufficiently conductive either by doping with a suitable dopant such as boron, arsenic or by the addition of small amounts of aluminum or other suitable metals. To use such silicon targets to create SiO2 thin films via DC or AC sputtering also requires that large amounts of oxygen be introduced into the sputtering process. The resultant process is referred to as reactive sputtering. The oxygen reacts with the silicon during the sputtering process to yield SiO2. To create SiO2 films typically requires that O2 gas pressure be 30 - 50% of the total gas pressure in the vacuum chamber. This can result in a significant process mismatch in terms of the oxygen requirements, as compared to that required for other sputtered thin films which may be deposited using the same vacuum vessel. The presence of significant O2 in the vacuum chamber also slows the deposition rate through collisions with the silicon. In addition, SiO2 films made by DC and AC sputtering from silicon or Si:Al targets generally are not sufficiently dense and crystalline as a result of the characteristics of reactive deposition to render them suitable for many semi-conductor, flat panel and optoelectronics applications. The SiO2 film compositions produced by such reactive processes generally exhibit less useful optical, mechanical and chemical durability properties compared to those produced by RF sputtering of non-conductive SiO2 targets.
SUMMARY OF THE INVENTION
[0005] It is an object of the present invention to produce silicon oxide-based material compositions (with the general formula SiOx) that include a sufficient amount of silicon to render the composition electrically conductive. The SiOx: Si material compositions of this invention are suitable for any application calling for electrically conductive SiOx-based material. One such use is as a target material for use in DC (including DC-pulsed) or AC sputtering processes to produce high quality SiOx thin film coatings with the addition of only small amounts of O2 during the deposition process, since the presence of SiOx in the target material serves as a source of oxygen in the vessel thereby decreasing the amount of oxygen gas that typically needs to be fed into the vessel during reactive sputtering DC or AC processes. This enables the production efficiencies of DC and AC sputtering to be used to produce SiOx coatings with properties that can be equivalent to those produced by the less efficient and more costly RF sputtering method.
[0006] The SiOx: Si material of the invention is composed of the constituent materials of electrically non-conductive SiOx and an amount of Si that has been doped and combined with the SiOx in a manner that physically unites the materials to render the overall SiOx-based composition electrically conductive. In some embodiments, there can be the addition of one or more metals in amounts smaller than that of the Si component. These material compositions, although primarily composed of insulating silicon dioxide, exhibit good electrical conductivity while retaining many of the other intrinsic material properties of the silicon oxide. Such materials can be fabricated in solid bulk forms such as plates, rods and tubes. In addition these bulk materials can be reduced (or reground) to powder form with such powders retaining the electrically conductive properties of the bulk material for use alone or with other materials in the formation of various articles of manufacture.
[0007] Accordingly, it is an object of the present invention to produce a composite SiOx: Si material which, although primarily composed of insulating SiOx material, has good electrical conductivity due to the presence of the Si material. This material may find use in many applications that require the optical, thermal, mechanical, or chemical properties of SiOx but which also require electrical conductivity to be useful. The electronic properties of this material can be adjusted based on the ratio of the constituents of electrically conductive doped Si, SiOx and in some embodiments small fractions of various metals.
[0008] According to a further aspect, particles of this conductive Si:SiOx material may be mixed or added to other materials to provide or enhance electrical conductivity or other useful properties.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawings, wherein:
[0010] Figure 1 is a schematic illustration of an article made of the Si: SiOx material; [0011] Figure 2 is a schematic illustration showing further details of the material; and [0012] Figure 3 is version of the material in particulate form. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0013] The present invention is directed to the formation of composite silicon oxide:silicon (SiOx: Si) material that is rendered conductive by the selection of starting materials and the process by which they are combined to form the composite. [0014] According to the fundamental principals of the present invention, the process starts out with a silicon oxide, SiOx powder (e.g., SiO2 powder) which is substantially electrically non-conductive. The SiOx powder is united with electrically conductive Si material in a manner that protects the Si against substantial oxidation during the process and which renders the overall composite electrically conductive while preserving the characteristics of each of the SiOx and Si materials. [0015] One approach contemplated by the invention starts out with a blend of SiO2 and conductive Si powders. The blended powder is compacted and sintered to form an article that has the properties of being similar to silicon oxide but with low resistivity, and thus they find use in many applications. For example, one particular usage for such a material is as a sputtering target suitable use in a DC or AC thin film sputtering process.
[0016] According to this first presently preferred embodiment of the invention, the conductive silicon component of the powder blend is prepared by crushing and then grinding doped silicon (such as boron p-type doped silicon) into a powder. As is well known to those skilled in the art, the doping of the silicon material may be achieved by adding a suitable n or p dopant to molten silicon prior to growing or casting the amorphous single or poly phase crystal of the silicon. The concentration and uniformity of these dopant atoms determine the specific electrical characteristics of the silicon.
[0017] The invention contemplates that various approaches can be employed to blend the particles of silicon oxide and conductive silicon and that variations can occur in the size of the particles and the ratio of the silicon oxide to doped silicon particles in order to alter the electrical conductive properties or resistivity of the end product. In the first presently preferred embodiment, the composition of the base silicon oxide powder is greater than 50% by weight, and that of the conductive silicon powder is greater than 10% by weight, with the silicon oxide preferably making up the majority of the powder blend. According one presently preferred process, the powders may be blended together in a pot using zirconia balls as milling media until the average particle size of the blended powder is reduced to less than 5μm. Once the powder has been sufficiently blended, it is preferably placed in a metal containment unit and then heated under vacuum conditions to eliminate residual moisture. Following heating to drive off the moisture, the containment unit is evacuated and sealed and then placed in a hot isostatic chamber and then heated to a temperature and pressure sufficient to densify and sinter the silicon oxide and doped silicon particles. For this purpose, the container is preferably one which can withstand the heat and pressure of the hot isostatic-pressing environment, but which flows plastically under the heat and pressure so as to consolidate and densify the powder material within the container. Once densified, the resultant article of silicon oxide-doped silicon material is removed from the container. The resulting composition is preferably densified to at least 90% of theoretical density, and preferably at least 95% of full theoretical density, and still more preferably greater than 99% of full theoretical density. According to a preferred process, the powder is subjected to hot isostatic pressure (HIP) at temperatures of between 1200 to 145O0C and under pressures exceeding 20 kpsi. More particularly, the preferred process involves hot isostatic press heating to 10000C under vacuum conditions and then gradually applying the pressure to more than 20 kpsi while increasing the temperature to between 1200 to 13500C. According to a further feature of the invention, the -resultant sintered article 10 has a resistivity value of less than 200Ω -cm. Preferably, the article or target has resistivity less than 150Ω -cm and still more preferably below 20Ω -cm and still further more preferably at or below 10Ω -cm. Accordingly, the range of resistivity contemplated by the invention is in the range of about 10Ω -cm or less to about 200Ω -cm.
[0018] Figure 1 schematically illustrates an article 10 made of the inventive material. Figure 2 schematically illustrates details of the material structure in which the non-conductive silicon oxide is present in a web of electrically conductive silicon. The conductive silicon serves as a conductive web that renders the overall material conductive.
[0019] Figure 3 shows a version of the material in particulate form. This material can be prepared by regrinding the sintered SiOx: Si material resulting from the process described above, or may be formed directly in particulate form by a process in which SiOx particles are coated with molten electrically conductive Si in a protective non- oxidizing atmosphere such as argon to cause the Si to at least partially coat and unite with the SiOx particles, while protecting the molten Si against oxidation in the process. The resultant composite particles can be mixed with other such particles and/or blended with an amount of uncoated silicon oxide particles and thereafter sintered to form an article. The amount of the conductive composite particles will be that amount which is needed to achieve the desired electrical conductivity properties. For example, the invention contemplates that enough of the composite particles are present to provide a conductive path through the bulk of the sintered material. [0020] Once the article is prepared, it can be used in a number of different applications, such as a target in a direct current (DC) or low to medium frequency alternating (AC) sputtering process for producing silicon oxide coatings. [0021] The invention contemplates that various manufacturing methods can be used to prepare the material that yield the same desirable characteristics and properties described above. These alternative methods can be used with or without the hot isostatic pressing. Such additional processes include vacuum plasma spraying of the Si material onto the SiOx material in an inert gas atmosphere to preclude oxidizing the Si; vacuum casting ("melt casting") of the materials to connect Si grains of the blend in the presense of the SiOx grains to yield a conductive network; vacuum hot pressing of the materials in an inert gas atmosphere; and inert gas microwave melting and solidification.
[0022] The invention also contemplates various post-treatment methods for rendering the Si conductive in the company of SiO2. m this case the Si is alone in powder form or united with the SiOx in reground powder form, with the Si initially being non-conductive. One alternative approach for making the silicon conductive is by means of thermal gas diffusion in non-oxygen atmosphere using a gas such as Arsine, AsH3 composition. Another approach is ion implantation with dopants such as Boron. It is also contemplated that the dopant such as Arsenic, Gallium, or Phosphorous could be added in powder form to reground non-conductive Si:SiOx powder and then sintered in a non-oxygen atmosphere. Still another approach to post- treatment doping of initially non-conductive Si is to mix metal powder such as Al, Mg, Sn, In, Mn, Zn, Bi, Cd, Se, and/or Ga with reground non-conductive Si:SiOx powder and then sinter in a non-oxygen atmosphere.
[0023] Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. The invention is defined by the claims.

Claims

What is claimed is:
1. A composite SiOx-based material, comprising: regions of SiOx material joined with discrete regions of conductive Si material, wherein the SiOx material is present in an amount between about 50% to about 80% by weight of the composite.
2. The material of claim 1 wherein the composite material is in powder form.
3. The material of claim 2 wherein the composite material is admixed with another material.
4. The material of claim 3 wherein the another material comprises SiO2.
5. The material of claim 2 wherein at least some the SiOx particles of the composite are substantially coated with the electrically conductive Si material.
6. The material of claim 1 wherein the composite material is sintered.
7. The material of claim 6 wherein the sintered composite material has a resistivity of about 200- Ω cm or less.
8 The material of claim 6 wherein the sintered composite material has a resistivity of about 20- Ω cm or less.
9. The material of claim 6 wherein the sintered composite material has a resistivity of about 10 Ω • cm or less.
10. The material of claim 6 wherein the sintered composite is compacted to at least 90% of full theoretical density.
11. A method of making conductive SiOx-based composite material, comprising: preparing SiOx powder; and joining conductive Si material to the SiOx material.
12. The method of claim 11 wherein the conductive Si is applied in one of liquid, gas or semi-solid form to the SiOx particles.
13. The method of claim 11 wherein the step of joining the Si material to the SiOx material is carried out in a non-oxidizing environment so as to protect the Si from oxidizing in the process.
14. The method of claim 11 wherein the SiOx powder is present in an amount between about 50% to about 80% by weight of the composite.
15. The method of claim 11 wherein prior to j oining, the Si material is prepared first in powder form and blended with the SiOx powder and thereafter compacted and sintered in a non-oxidizing environment.
16. The method of claim 15 wherein the compacted and sintered composite material is formed with a density of at least 90% of full theoretical density.
17. The method of claim 11 wherein the composite material is formed with a resistivity of about 200 Ω • cm or less.
18. The method of claim 11 wherein the composite material is formed with a resistivity of about 20 Ω •• cm or less.
19. The method of claim 11 wherein the composite material is formed with a resistivity of about 10 Ω • cm or less.
20. A method of making conductive SiOx-based composite material, comprising: preparing SiOx powder; and joining Si material to the SiOx material and doping the Si material to render it conductive.
EP06801634A 2005-08-11 2006-08-11 Siox:si composite material compositions and methods of making same Withdrawn EP1925003A4 (en)

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EP2294004A1 (en) * 2008-07-09 2011-03-16 Degussa Novara Technology S.p.A. Silicon-based green bodies
KR102347960B1 (en) 2015-02-03 2022-01-05 삼성전자주식회사 Conductor and method of manufacturing the same
CN113526516B (en) * 2021-09-16 2021-12-03 北京壹金新能源科技有限公司 Modified silicon monoxide and preparation method and application thereof

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KR20080044267A (en) 2008-05-20
US20070034837A1 (en) 2007-02-15
WO2007022276A2 (en) 2007-02-22
CN101405426A (en) 2009-04-08
WO2007022276A3 (en) 2008-10-16
JP2009504556A (en) 2009-02-05
TW200729234A (en) 2007-08-01

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